Jahnen, B. (Corresponding author)FZJ*

2002
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich

Report No.: Juel-3953

Abstract: Interdiffusion in alloys based an the GaSb-AlSb material system that is suitable for optoelectronic devices for the infrared range is investigated quantitatively and is interpreted in terms of an atomistic model . To this end, nominally undoped GaSb/Al$_{x}$Ga$_{l-x}$Sb heterostructures were subjected to thermal treatment under both Sb-rich and Ga-rich conditions in the temperature range of 600 °C to 700 °C. For characterisation of the heterostructures, transmission electron microsocopy (TEM) and X-ray diffraction were applied. For quantitative analysis of concentration profiles an a nanometer scale, a TEM bright-field technique was developed that is based an a symmetric five-beam imaging condition with excitation of the systematic row of {200}-beams. It is shown that interdiffusion in the GaSb-AlSb system can be described by a concentration-dependent interdiffusion coefficient. Interdiffusion is retarded with increasing aluminium concentration x of the Al$_{x}$,Ga$_{1-x}$Sb alloy. Under Sb-rich conditions, interdiffusion is significantly faster than under Ga-rich conditions. The present study shown that the mechanism of interdiffusion of the group-III atoms in the GaSb-AlSb system can be described in terms of vacancies an the group-III sublattice. Under Sb-rich conditions, evaporation of group-III atoms into the gas phase leads to a high concentration of group-III vacancies. Under Ga-rich conditions, these vacancies are created indirectly by formation of group-III antisites. The equilibrium concentration of the group-III vacancies is identified as the relevant factor for the observed experimental results.

Keyword(s): III - V semiconductor ; heterostructure ; diffusion

1. Mikrostrukturforschung (IFF-8)